RESUMEN
Gindenosides are the active ingredients of Panax ginseng. 20 (S) -protopanaxadiolocotillol type epimers are the main metabolites of 20 (S) -protopanaxadiol. The previous studies showed that there are stereoselectivity difference in pharmacodynamics and pharmacokinetics between 24R-epimer and 24S-epimer. The purpose of this study was to explore the excretion of the epimers in bile, feces and urine of rat. Liquid chromatography tandem mass spectrometry method has been performed for determination of 24R-epimer and 24S-epimer in bile, feces and urine. 24R-epimer or 24S-epimer was intragastric administered to rats at a single dose of 10 mg x kg(-1). Results showed that after administration the recovery of 24R-epimer and 24S-epimer in feces was 17.69% and 17.09%, respectively, while both of the two epimers were hardly detected in urine. The 48 h cumulative biliary excretion rate of 24R-epimer was 8.01% after administration, while only 1.47% for 24S-epimer. It indicated that there are stereoselectivity in biliary excretion of the epimers with intragastric administration.